3. Informing the results of screening test: All the participants will receive the results one week after their screening. Based on the screening results, all participants will be categorized into three groups: (1) infected (HbsAg+), (2) unprotected (HbsAg-/HbsAb-), and (3) protected (HbsAg-/HbsAb+). The investigators will order all screening tests and review all test results from the certified clinical labs. The investigators will mail the results to participants who are unprotected and protected. The investigators will not follow up healthy participants who are protected. The investigators will be responsible for informing the results by calling those infected individuals. The participants will provide counseling on what the results mean and treatment options.